Gauss Plane Coordinate's Influence By Change Of Ellipsoidal And Projective Parameter

With the development of spatial technology, the national geodesic coordinate system has a lot of problems in China, and begins to lose its practicability and advantage. To establish a new national geodesic coordinate system according with the International General Coordinate System is a certain developing trend of the geodetic survey plane datum in China. At the same time, our national economy is developing at very fast speed, some city scale is extending continuously, and the former city control network can not satisfy city building, so the city control network must be established over again at intrinsic base.If the national geodesic coordinate system were replaced, namely reference spheroid parameter were be changed, ground-point's Gauss plant coordinate could be changed. Once the city control network were be established over again, how to choose appropriate central meridian, how to carry out the coordinate transformation and how to effectively limited the distance distortion, are always problems concerned by surveyors.This paper introduces a series of basic geodesic theories including reference spheroid, isometric design, Gauss Projection Series, coordinate transformation etc. , discusses the change of Gauss plane coordinate with the change of long-radius and flattening of reference spheroid and the change of central meridian and projective surface. The research content as follows:Firstly, according to projection theory, when the reference spheroid's geometrical parameter changes, it finds that Gauss plane coordinate discrepancy is δx = δX + δR + δT , δy = δS + δK;and it analyzes Gauss plane coordinate discrepancy of every crossing point in this latitude-longitude grid of longitude difference 10' and latitude 5° in 3° scope. But in fact the factor of other spheroid parameter must be taken into account.Secondly, according to projection theory, when the central meridian changes, it finds that Gauss coordinate discrepancy is δx = X + Aδ(l")~2 + Bδ(l")~4 + Cδ(l")~6,δy = Dl" + Eδ(l")~3 + Fδ(l")~5;analyzes Gauss coordinatediscrepancy of every crossing point in this latitude-longitude grid of longitude differencelO' and latitude 10' inl°scope;and advice that the problem is settled by means of planar coordinate transform.Thirdly, according to isometric design' condition , it finds how to calculate planar coordinates of Gauss Projection Series, and compares Universal Transverse Mercator Projection(UTM) and Double-standard Longitude Isometric Projection Gauss Projection, offers distance distortion by these projections;at last, two projection models are brought forward that could effectively limited distance distortion.In the finality, the problems requiring further studies are discussed.